PENSACOLA, Fla.  Football players usually hoot and holler when viewing tapes of bone-crunching hits.

Recently, however, the West Florida High Jaguars could only gasp and cringe as they watched clip after clip of tackles that broke necks and damaged brains.

That's the reaction Indianapolis Colts coach Tony Dungy and a coalition of sports doctors and trainers hope to get with "Heads Up," a DVD being distributed to high school football teams nationwide.

Annually, between four and 12 football players from youth leagues through the pros suffer paralyzing injuries each year, according the National Athletic Trainers Association (NATA).

Many others suffer severe spine and brain injuries because of improper tackling  hits made with the crown of the head instead of the shoulders  or helmet-to-helmet contact.

"What we are concerned about is that one hit that can cause a quadriplegic, the perfect storm that happens when the neck is (not) in the right position," said Ron Courson, an athletic trainer at the University of Georgia who's featured in the video.

"We are not trying to scare them. Football is a violent sport, and we want the defenders to be aggressive. But when you lower your head down, you take away the normal curve in your neck that allows for shock absorption."

Chris Canales of San Marcos, Texas, hasn't moved his body below his chest since Nov. 2, 2001, when the all-conference defensive back and punter fractured his spinal cord on a touchdown-saving tackle for San Marcos Baptist Academy.

Following the injury, Canales and his father, Eddie, founded the Gridiron Heroes Spinal Cord Injury Foundation. They travel Texas providing moral support and raising money for other paralyzed high school football players.

Of the 14 "Gridiron Heroes" they help, "pretty much all of them were the same type of injuries where the heads were down," Eddie Canales said.

"Heads Up" will cause players to think before they lead into tackles with their heads, he said. "This is great, because it is on the prevention side.

"The thing for so many of these kids is that they need sports. I wouldn't deter anyone from playing football. Driving a car is more dangerous."

Chris Canales, now 23, said coaches, especially those in peewee football, should see the video, but many avoid discussing paralysis or permanent brain injuries with their players.

"I don't think anybody likes to talk about the injury, but it's out there and it needs to be prevented," he said.

World-renowned orthopedic sports surgeon Dr. James Andrews and his Gulf Breeze, Fla.-based Andrews Institute for Orthopedics and Sports Medicine funded the distribution of the video after NATA sought his help.

The association produced the video and provided it to the NCAA last year. But Andrews said coaches and trainers feared the message wasn't reaching the audience that needed to hear it most  high school and youth league players.

West Florida High coach Ronnie Gilliland has 34 years' coaching experience and can describe devastating hits, but he's no match for the video.

"The video really made them realize that these things can happen," he said.

Josh Hyde, a 16-year-old junior offensive lineman, sat in the front row, cringing as messages flashed on the screen after many of the hits stating they had led to permanent quadriplegia.

In the video, doctors use graphics to demonstrate how vertebra in the cervical spine are crushed when the head hits.

"You just have to keep your head up, so your neck doesn't get hurt," Hyde said. "It's something the coach always tells us to do."

With the video, NATA also is pushing officials at all levels to be more aggressive in calling penalties for spearing, when a player plows into another with the crown of his helmet. Officials often call a personal foul instead. Both are 15-yard penalties, but the association says players would learn to stop spearing if the specific call were made.

"It is bolded in the rule books, and this something that we want to see more emphasis on," Courson said.

The association also wants TV football commentators to do their part.

"We hope they will say what constitutes a good hit and what constitutes a bad hit," Courson said.

That information is too late to help Preston Plevretes.

Two years ago, the 21-year-old was covering a punt for LaSalle University when another player's helmet collided with his. He immediately suffered a series of strokes, and his brain swelled.

"I have a picture of him in the hospital with tubes and electrodes coming out all over him, and he has no skull," said his mother, Tammy Plevretes. "If any kid sees that, it will scare the hell out of them."

Two years later, Preston has no short-term memory and struggles to walk.

"I never thought that could happen to my son playing football," his mother said. "If anything, I thought maybe a broken arm or a broken leg. And two years later, he is still struggling today. He cannot walk without a walker."